Bio:Krypto is a purebred dog of a breed known only on the planet Krypton. In appearance he is close but not identical to a smooth-haired terrier.

Krypto was bought by Jor El II for his small son Kal-El. Krypto had a normal puppy's life until a short time before the destruction of Krypton. Since space travel had been outlawed by the Science Council, Jor El II had to act in secret and had a difficult time procuring test animals for his spaceship experiments. Thus he had to use Krypto in one small rocket model.

The rocket went into orbit beautifully, but it was then struck by a stray meteor that knocked it out of orbit. Presumably the jolt caused the rocket engine to fire; otherwise, the ship would have fallen to the surface instead of hurtling into space as it did. Fortunately, the life support system kept the pup alive for the 58 days before the explosion that destroyed Krypton. Then, when little Kal-El's spaceship opened a space-warp to Earth's solar system Krypto's rocket was drawn into it.

Once under Earth's yellow sun, Krypto became a super-dog, but still could not escape from the rocket since it to had become indestructible. Aside from confinement, Krypto suffered no ill effects, since he did not need to eat.

Finally, the spaceship came to Earth, crashing into a deserted field a great distance from the town of Smallville. However, with his super-memory and super-senses Krypto was able to track the familiar odor if his former master to Smallville and was reunited with Clark Kent.

Krypto led Superboy to his rocket (which had jolted open on impact) and in it Superboy discovered the record of the experiment placed there by Jor-El II.
Krypto first imperiled Superboy's secret identity, as he could sense that Clark Kent was his master. Superboy manage to cover up, and eventually taught the pooch to help him protect his identity.
In a secluded area, Superboy built a stone doghouse for his pet. and later used leftover threads from his costume to make a cape for Kypto. But Krypto preferred to spend most of his time romping in space.

However, when at home in Smallville, Krypto disliked having to hide. Therefore, he got the idea of creating a wood-stain spot on his back and so having a secret ID of his own. He became Clark Kent's dog, Skip. When he had to go into action he would burn away the spot with his heat vision then slip into his collar and cape (hung on a hook), and exit through the secret tunnel used by Superboy.

For a few years Krypto vanished. When he finally returned, Superboy had grown up to be Superman (Earth-1), and Krypto was old and in poor shape. Superman sent him to a valley surrounded by Kryptonite meteors. A spring there had become a "fountain of youth" that rejuvenated the dog and made him temporarily immune to Kryptonite, so he was able to escape. (What happened to the spring after all Kryptonite then on Earth turned to iron is not known.)

Finally, out in space Krypto used his heat vision to weld some meteoroids into a Doghouse of Solitude somewhere in space.